1. Field of the Invention
The present invention is appropriately applicable to medical fields, and relates to an apparatus, method and computer program for assisting a user in image-based diagnosis performed based on three-dimensional image data.
2. Description of the Related Art
In recent years, high quality three-dimensional image data became obtainable by an advance in modalities, such as a multi-slice CT (MDCT: Multi Detector Computer Tomography). In image-based diagnosis using such image data, not only a high definition tomographic image but also a virtual pseudo-three-dimensional image of a subject to be examined became used. Further, as disclosed in the specification of U.S. Patent Application Publication No. 2009/0238431 (Patent Document 1), an organ region is extracted from a three-dimensional image by using an image recognition technique. Therefore, a virtual pseudo-three-dimensional image became producible from a three-dimensional image in which a structure had been identified more clearly. The produced image is used also for planning or simulation before surgery and for navigation during surgery.
Here, in CT examination of a large intestine, when large intestinal contents are insufficiently removed from the large intestine, the large intestinal contents appear as a residue in a CT image. If the CT value of the residue and the CT value of the wall of the large intestine (or a polyp in the large intestine) are about the same, it is difficult to distinguish the wall of the large intestine and the residue from each other also in a tomographic image. As a technique for solving such a problem in CT examination of the large intestine, radiography is performed on a patient with two body positions of a supine position and a prone position in some cases. In radiography at two body positions of a supine position and a prone position, the phenomenon that a residue moves when a body position changes is utilized, for example, as disclosed in Japanese Unexamined Patent Publication No. 2012-187161 (Patent Document 2) and Japanese Unexamined Patent Publication No. 2010-264232 (Patent Document 3). Even if a part of the large intestine is not observable in one of the images because of the residue, it is possible to observe the part in the other image by reading corresponding positions in the images obtained by radiography at two body positions of a supine position and a prone position.